GI Caustics - Artefacts

[morentz]

He guys, digged out my car again after a few month of pause

Got a big little problem. Whenever rendering glass I get some artefacts in my scene.

The following images should illustrate my problem.

The first rendering without the windows:

Attachment 56739

The Second whith the windows but GI Caustics turned off - this means, no indirect light travels through refractive surfaces, right?!

Attachment 56740

So, now with GI Caustics On and the Windows - but low settings

Attachment 56741

As you can see in the marked areas there are little light spots / caustics caused by the vray light in the scene. Vray Dome light don't cause that glotches.

And here, same again whith higher settings - can be seen in the image itself

Attachment 56742

Now the question: How do I prevent those caustics / artefacs?!

My Settings:

Glass Material
DIFFUSE = pure Black
REFL. = nearly white with fresnel on
REFR. = white
Reflect on backside is on

All windows are unchecked at generate / recieve shadows - allready tested -> no difference

GI = on
Adaptive DMC fromt 1 to 2 and clr. thr. 0,01
First Bounces: Irriance -> low
Second Bounces: Light Cache (500)

all other settings are default

Thats all =)

Thanks for your help !

[Duron]

Go to Vray Color Mapping and turn on Sub-Pixel Mapping

[morentz]

thanks jaystyle for your quick answer, but it Didn't work :banghead:

It's something about the vray lights. There are two of them in the exact same place. One bigger and one smaller.

The bigger one (~160 cm) causes these artefacts, the smaller (10 cm) doesn't.

I attached the szene (max 2010) - it would be nice if someone would have a look at it

cheers

[exidge]

Hemispheric subdivs controls the quality of individual GI samples. Smaller values make things faster, but may produce blotchy result. Higher values produce smoother images. Try to increase the Hsph. subdivs. multiplier to avoid artefacts.

Cheers,
exidge

[morentz]

Strange! Posted a reply 2 days ago and now it's gone ... Thanks for that exidge! Whith more HSph. sub. it comes closer to what I'm looking for but rendertime goes up to incredible heights and the result is still not satisfying. I found a work around ... under the refraction settings of the material check "affect shadows" now all my artefacts are gone without an effect on rendertime Thanks anyway for your help! greetings